N-cyclopropyl-pyridyl carboxamide derivatives

ABSTRACT

COMPOUNDS HAVING THE FORMULA:   R1,R2,(CYCLOPROPYL-NH-CO-)-PYRIDINE   WHEREIN R1 IS AN ALKOXY GROUP OF 1 TO 6 CARBON ATOMS AND R2 IS AN ARYLOXY GROUP OF 6 CARBON ATOMS WHICH MAY BE SUBSTITUTED. THESE COMPOUNDS ARE USEFUL IN THE TREATMENT OF DISEASES OF THE NERVOUS SYSTEMS IN HUMANS AND ANIMALS, E.G. MICE.

United States Patent Ofice 3,822,278 Patented July 2, 1974 US. Cl. 260295 AM 14 Claims ABSTRACT OF THE DISCLOSURE Compounds having the formula:

/CH2 ONE-CH2 wherein R is an alkoxy group of 1 to 6 carbon atoms and R is an aryloxy group of 6 carbon atoms which may be substituted. These compounds are useful in the treatment of diseases of the nervous systems in humans and animals, e.g. mice.

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part of application Ser. No. 238,963 filed on Mar. 28, 1972, which application is a continuation of application Ser. No. 807,395 filed Mar. 14, 1969.

This invention relates to various novel compounds having an amide function and showing particularly interesting pharmacological properties which allow their use in animal or human therapy, and the preparation of these compounds. Heretofore, it has been described in the pending application Ser. No. 238,963, filed Mar. 28, 1972, which application is a continuation of application Ser. No. 807,395, filed Mar. 14, 1969, that compounds having the general formula:

wherein n is 0, 1 or 2 and -R is one or several members selected from the group consisting of hydrogen and halogen radicals halogen referring to chlorine, bromine, iodine or fluorine atoms), hydroxy groups (which can be acrylated with carboxylic acids having 1 to 4 carbon atoms), carboxylic acid groups (which can be esterified or amidated), sulfonic acid groups (which can be amidated), and hydrocarbon groups from 1 to 8 carbon atoms which can be branched or cyclic and which may contain one or several multiple-bonds are useful in such therapy. The carboxylic cyclopropylamide group as well as the described substituents R may occupy any of the positions on the pyridine ring. These compounds have particularly interesting properties which allow their use in various applications.

Moreover, it is well known from French Pat. No. 1,524,761 of Abbott Laboratories that some amides of 2-6 dichloroisonicotinic acid and particularly N-cyclopropylamide have sedative properties.

In accordance with this invention, particularly interesting properties for compounds having a general formula similar to that heretofore described have been found wherein R represents two groups, one being a halogen and the other an alkoxy or aryloxy group. These new compounds can be represented by the formula:

wherein R is a halogen group, i.e., a chloro, bromo or fluoro group and R is an alkoxy group of 1 to 6 carbon atoms, which may be cyclic, branched or straight chain or an aryloxy group of 6 nuclear carbon atoms constituting a cyclic chain which can be substituteed with one or more substituent groups such as the lower alkyl, i.e. methyl ethyl, and propyl or halogen groups, i.e., chloro, bromo, or fluoro or both alkyl and halogen groups. The described carboxylic cyclopropylamide group and the R and R substituents may occupy any of the positions on the pyridine ring.

The present invention also is concerned with the salts of these new compounds with mineral or organic acids, as well as the addition derivatives thereof through the nitrogen of the pyridine nucleus, such as the halo-alcoholates, the sulfo-alcoholates and the amine oxides.

The present invention also is directed to the preparation of the compounds described hereinabove through the methods described below.

The present invention relates also to the intermediate compounds which can be used to obtain the above-described compounds, as far as these intermediates were not known until now.

This invention is particularly directed to the compounds having an N-cyclopropylcarboxamide group in the 4 position from the nitrogen of the pyridine nucleus and having the substituents R and R in the 2 and 6 position. These compounds have the following formula:

4 -2L1 6 R1 N The compounds according to the invention can be prepared from a pyridine-carboxylic acid having already 2- halogen groups and by substituting only one of these groups by the alkoxy or aryloxy group, this substitution being carried out either on the acid itself or on a functional derivative of it.

The carboxylic acid or the functional derivative used are thereafter transformed to an amide function by use of the usual methods of organic synthesis.

As a functional derivative, an ester of the carboxylic acid with an alcohol of low molecular weight may be used. It is also possible in some cases to obtain the required compound with only one reaction from the cyclopropylamide of the dihalogen pyridine carboxylic acid, after substitution of one of the halogen groups by an alkoxy or aryloxy group.

All these reactions can be illustrated by the following formulas:

0NH- o 0 OH O 0 OH The following examples concerning the preparation of the compounds of the present invention are given merely as illustrative and are not to be considered as limiting, particularly concerning details of reactions such as solvents, temperature, concentration of the reagents, time of reaction, etc.

EXAMPLE 1 Preparation of chloro-2 methoxy-6 N-cyclopropyl carboxamido-4 pyridine (a) Preparation of chloro-2 methoxy-6 carbox'ymethyl- 4 pyridine: A suspension of 150 gr. of dichloro isonicotinic acid (prepared according to the process described in the Chemical Handbook Houben-Weyl, Volume 5/3, page 925) in 160 ml. of thionyl chloride is heated to reflux during 3 hours. A slight insoluble is filtered. The thionyl chloride in excess is concentrated and the residue is distilled under vacuum.

Obtained in this manner are 108 gr. of 2,6-dichloro isonicotinic acid chloride boiling at 119 to 121 C. under mm. pressure.

This chloride is poured while cooling in excess anhydrous methanol, leading to a clear solution and after some time, the methyl ester crystallizes in the form of white needles with a melting point at 81 C. (Kofler).

100 gr. of methyl ester thus obtained is dissolved in 300 ml. of methanol and stoichiometric quantity of sodium methylate is added thereto.

The reaction mixture is heated to reflux until a neutral reaction is obtained. By concentration of the liquor in vacuo, recovery in water and washing according to the usual methods, the methyl ester of chloro-2 methoxy-6 isonicotinic acid is thus obtained in the form of white crystallized product which melts at 134 C. (Kofler) The yield reaches 75% (b) N-cyclopropylamide of chloro-2 methoxy-6 isonic0- tinic acid or chloro-2 methoxy-6 N-cyclopropylcarboxamide-4 pyridine: To a suspension of 0.074 mol. of the above compound (a) in 80 ml. of ethylene glycol is added 0.3 mol. of cyclopropylamine. The mixture reaction is stirred at 50 C. for one hour.

Thereafter, everything is passed into solution, then a white solid begins to separate. The mixture is maintained at 50 C. for another 70 hours, then it is cooled and the crystallized product is centrifuged.

The material recrystallized from methanol is obtained as white cottony needles and having melting point at 136 C. (Kofler).

When subjected to the elementary analysis, this product gives the following figures: C, 53.15%; H, 5.13%; N, 12.70%; Cl, 15.42%. Calculated for C1QH1103N2C1 (226.5

4 mol. wt.): C, 52.99%; H, 4.89%; N, 12.36%; Cl, 15.64%.

The coincidence of the figures found with the theoretical values establishes with certainty the structure of the new compound.

The product thus obtained, i.e., chloro-2, methoxy-6, N-cyclopropyl carboxamido-4 pyridine is soluble in alcohol at the rate of about 5% and slightly more soluble in acetone and methanol.

It is almost insoluble in water.

EXAMPLE 2 Preparation of N-cyclopropylamide of chloro-2 methoxy-6 isonicotinic acid This product can also be prepared from N-cyclopropylamide of 2,6-dichloro-isonicotinic acid by operating in the following manner:

To a solution of 0.5 gr. sodium (0.0217 mol.) in 20 ml. of methanol is added in one time 5 gr. of 2,6-dichloro- N-cyclopropylisonicotinic amide (prepared by -reacting the acid chloride with cyclopropylamine and having a melting point at 149-151 C. (Microscope).

The mixture is heated to reflux for 30 minutes, then concentrated by half and 200 ml. of water is added.

The white crystals thus prepared are centrifuged and dried and recrystallized in methanol.

The product obtained has a melting point at 134-l36 C. (Kofler) and after mixing it with a sample prepared according to Example 1, the melting point does not show any decrease.

' EXAMPLE 3 Preparation of chloro-2 phenoxy-6 cyclopropylcarboxamido-4 pyridine (a) Preparation of chloro-2 phenoxy-6 isonicotinic acid: To the solution of 19.2 gr. (0.1 mol.) of dichloro-isonicotinic acid in ml. of dimethyl sulfoxyde is added 11.6 gr. of sodium phenate. The mixture is heated at 130 C. for 10 hours.

After elimination of the solvent under vacuum, recovery of the residue with water and acidification, an oil is separated and recrystallized in isopropyl oxyde.

The chloro-2 phenoxy-6 isonicotinic acid is obtained as slightly cobured crystals with a melting point at 167 C. (Kofler).

This acid is refluxed toluene with an excess of thionyl chloride till the end of gas emission. Thereafter, the toluene is concentrated in vacuo, yielding chloro-2 phenoxy-6 isonicotinic acid chloride as a mobile oil.

(b) Chloro-2 phenoxy-6 N-cyclopropylcarboxamido-4 pyridine: To a solution of 10 gr. (0.037 mol.) of the above acid chloride in 50 ml. of dry benzene is added 2.1 gr. (0.037 mol.) of cyclopropylamine.

Everything passes in solution, then a crystallized product separates which is centrifuged, dried and recrystallized in 7 volumes of benzene.

The chloro-2 phenoxy-6 N-cyclopropylcarboxamido-4 pyridine is obtained in the form of white crystals melting at 147 C. (Kofler) and giving the following analytical data: Cl, 12.47%; N, 9.84%; C, 61.6%; H, 4.59%. Calculated for C H ClN O (288.5 mol. wt.): C], 12.28%; N, 9.70%; C, 62.4%; H, 4.54%.

EXAMPLE 4 Preparation of chloro-2 ethoxy-6 N-cyclopropylcarboXamido-4 pyridine By operating as indicated in Example 1, but using sodium ethylate instead of methylate, the chloro-2 ethoxy-6 carboxymethyl-4 pyridine is obtained which can be transformed easily in chloro-2 ethoxy-6 N-cyclopropylcarboxamide-4 pyridine. The product thus obtained is a white crystalline powder melting at C. and giving the following analytical data: C, 55.25%; H, 5.35%; N, 11.40%; Cl, 14.9%. Calculated for CuHmClNgOg mol. wt.): C, 53.90% H, 5.44% N, 11.63% Cl, 14.7%.

This compound can also be prepared accordingto- Example 2 by operating in the following manner:

To a solution of 1.5 gr. sodium (0.065 mol.) in 60 ml. of ethanol is added 15 gr. (0.065 mol.) of 2-6 dichloroisonicotinic cyclopropylamide.

The mixture is brought to reflux for 2 hours, and after pouring in 300 ml. of water, the product separatesyie'lding crystals which are centrifuged and recrystallized in methyl ethyl ketone.

The recrystallized product melts at 115 C. (Kofler) as the product prepared with the first method.

EXAMPLE 5 Preparation of ehloro-2 n-butoxy-6 N-cyclopropylcarboxamido-4 pyridine By operating in an analogous manner to that outlined in Example 4, this compound is easily prepared in the form of white crystals melting at 101 C. after recrystallization in methyl ethyl ketone. Subjected to elementary analysis, it gives the following figures: C, 58.30%; H, 6.45%; N, 10.60%; Cl, 13.4%. Calculated for (268.73 mol. Wt.): C, 58.13%; H, 6.52%; N, 10.42%; Cl, 13.18%.

EXAMPLE 6 Preparation of chloro-2 iso-butoxy-6 N-cyclopropyl carboxamido-4 pyridine By operating as above, this compound is obtained in the form of white crystals melting at 129 C.

Subjected to elementary analysis, it gives the following figures: C, 57.98%; H, 6.47%; N, 10.65%; Cl, 13.1%, Calculated for C13H11C1N202 (268.73 mol. wt.): C, 58.13%; H, 6.52%; N, 10.42%; Cl, 13.18%.

EXAMPLE 7 Preparation of chloro-2 para-chlorophenoxy-6 N-cyclopropylcarboxamido-4 pyridine is iz a a a (323.18 mol. wt.): C, 55.74%; H, 3.74%; N, 8.67%; Cl, 21.94%.

This product is insoluble in water, soluble in methanol and hot ethanol. By operating in analogous manner, the following products have been prepared:

bromo-2 methoxy-6 pyridine carboxylic-4 acid bromo-2 ethoxy-6 pyridine carboxylic-4 acid bromo-2 propoxy 6 pyridine carboxylic-4 acid bromo-2 butoxy-6 pyridine carboxylic-4 acid as well as the corresponding N-cyclopropylamides:

bromo-2 methoxy- 6 N-cyclopropylcarboxamido-4 pyridine bromo-2 ethoxy-6 N-cyclopropylcarboxamido-4 pyridine bromo-2 propoxy-6 N-cyclopropylcarboxamido-4 pyridine bromo-2 butoxy-6 N-cyolopropylcarboxamido-4 pyridine The products, i.e. the N-cyclopropylcarboxamido-eontaining compounds, of the present invention have a great activity on the central nervous system and a very low toxicity.

These compounds have a LD 50 between 1,000 and 8,000 mg./kg. as measured orally in mice.

In rats, the toxicity observed is slightly, the LD 50 being included between 500 and 2,000 mg./kg.

In both cases, due to the small solubility of the products, they have been administered orally in oil or aliginate suspensions.

These compounds according to the invention show anticonvulsant effects which result in the inhibition of convulsions and mortality induced by pentylenetetrazol and picrotoxin.

As an example, the following results as obtained in mice with chloro-Z methoxy-6 N-cyclopropylcarboxamido-4 pyridine are given below:

Percent of survivals The products according to the present invention show equally an hypnotic activity which is manifested by a direct hypnosis at doses from 50 to 250 mg./kg., as well as by a potentialization of the sleep produced by chloral hydrate and hexobarbitol. The central sedatives effects of the products according to the invention have equally been shown by the hole board test of Boissier, the rota-rod test, the chimney test and the evasion test. Moreover, the products according to the invention show at various grades analgesic properties.

The present invention also contemplates formation of salts of the compounds described above with all mineral or organic acids, as well as the addition derivatives through the nitrogen atom such as bromo-methylate, iodo-methylate or aminoxyde as well as their use in various industrial and more specially pharmaceutical applications, either separately or in combination with other active principles or excipients and in all pharmaceutical forms such as tablets, cachets, capsules, suppositories, drinkable solutions or injectable preparations for treating all nervous system diseases.

What is claimed is:

1. A N-cyclopropylcarboxamide derivative of pyridine having the formula:

wherein R is a member selected from the group consisting of chloro, bromo and fluoro groups and R is an alkoxy group of 1 to 6 carbon atoms, either cyclic linear or branched, or an aryloxy group of 6 nuclear carbon atoms which may be substituted with at least one halogen group or at least one methyl, ethyl or propyl group.

2. A compound according to claim 1, wherein R is chloro, and R is an alkoxy group of 1 to 6 carbon atoms which may be branched.

3. A compoundaccording to claim 1, wherein R is chloro, and R is an aryloxy group which may be substituted with at least one halogen group or with at least one methyl, ethyl or propyl group.

4. A compound according to claim 2, wherein R and R are in the 2- and 6-positions and N-cyclopropylcarboxamide in the 4-position.

5. A compound according to claim 3, wherein R and R are in the 2- and 6-positions and N-cyclopropylcarboxamide in the 4-position.

6. Chloro 2 methoxy-6 N-cyclopropylcarboxamido-4 pyridine.

7 7. Chloro-Z phenoxy-6 cyclopropylcarboxamido-4 pyridine.

8. ChIoro-Z eth0xy-6-cyc1opropylcarboxamido-4 pyridine.

9. Chloro-Z butoxy-6N-cyclopropylcarboxamido-4 pyridine.

10. Chloro- 2 chlorophenoxy-6N-cyclopropylcarboxamido-4 pyridine. 1

11. Bromo-2 methoxy-6 N cyclopropylcarboxamide-4 pyridine.

12. Bromo-Z ethoxy-6 N-cyclopropylcarboxamido-4 pyridine.

13. Bromo-Z propoxy-6- N-cyclopropylcarboxamid0-4 pyridine 8 14. Bromo-2 butoxy-6 N-cyclopropylcarboxamido-4 pyridine. I

References Cited UNITED STATES PATENTS 3,398,155 7/1968 Horrom 260-295 AM ALAN L. ROTMAN, Primary Examiner U. S. c1. X.R. 260295.5 A; 424266 

